Author: Robert Hyatt
Date: 21:46:01 01/21/02
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On January 21, 2002 at 10:55:50, Daniel Clausen wrote: >Hi > >On January 21, 2002 at 10:41:39, Robert Hyatt wrote: >[snip] >>1. If you get a fail high at the root on a zero-width window (any move after >>the first move should be searched with a zero-width window) you can't trust it >>unless you re-search it with a bigger beta bound and make _sure_ that it doesn't >>then fail low. Such fail-high (zero window) fail-low (non-zero window) is an >>artifact of null-move and if you play such a fail high move even if it fails low >>on the re-search, you will die... > >Anyone has a trivial example at hand which demonstrates this behaviour? > >Why is it that a fail-high with a zero window can't be trusted but a fail-high >with a non-zero window can? Is "non-zero window" enough to be trusted? Or does >it have to be a certain minimum window? I'm sure that as soon as someone posts a >mini-example which shows this behaviour, even I will understand it. :) > >Sargon I don't have an example now as I found this bug several years ago and then eliminated it as I explained. It is an artifact of mixing null-move with the null-window PVS search.
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